Lieutenant General Marcus John Slade (22 January 1801 – 7 March 1872) was a British Army officer who became Lieutenant Governor of Guernsey.
Slade was the fourth son of General Sir John Slade, 1st Baronet (1762–1853) and the younger twin brother of Sir Frederic Slade, 2nd Baronet, who succeeded their father in the baronetcy.His youngest brother by his father's first wife was Admiral Sir Adolphus Slade.